Trick riding on cycles, especially bicycles, is becoming increasingly popular in sport and competition activities. There are two types of cycle hubs, and each is more amenable to certain kinds of tricks than the other. In fact, certain tricks can be done on one but not on the other type.
One type of hub is the coaster brake hub. In this device, forward rotation of the pedals drives a hub sprocket to propel the cycle forwardly. Because the pedals and the pedal sprocket are directly linked by a chain to a hub sprocket, the hub sprocket movements will be understood to be the same as those of the pedals in both types. In the coaster brake hub, forward driving of the hub sprocket drives the hub shaft forwardly so the wheel propels the cycle forwardly. Rearward rotation of the hub sprocket is limited, because after a rearward rotation of only a few degrees, the coaster brake is applied, and the cycle is brought to a stop.
The freewheeling type also drives the hub shaft forwardly when the hub sprocket is rotated forwardly. However, rearward rotation of the hub sprocket, and therefore of the pedals is free and unrestrained. It is this action which is referred to herein as "freewheeling". No brakes are applied. In conventional freewheel cycles, the brakes are controlled by levers on the handle bars, and the brakes themselves are calipers which press against the wheel to brake its rotation.
These two types of hubs have inherently different properties with respect to various tricks. For example, for some tricks it is necessary to have the pedals at a particular orientation at the start of the trick. However, forward rotation moves the cycle, perhaps to an undesirable place, and with the coaster brake hub rearward rotation applies the brakes, which may be undesirable. The evident solution is to use a freewheeling hub for these tricks. But what if one owns only a cycle with a coaster brake?
The brute force solution to this quandary, which is common these days, is to own two cycles, each with a different hub, or to have one cycle with two different rear wheel assemblies, and to change wheels between tricks. These are troublesome and expensive solutions.
It is an object of this invention to provide an integral cycle hub which can readily be converted from freewheeling to coaster brake operation, and vice versa, without changing the wheel hub.
A cycle hub according to this invention has a hub sprocket driven by a chain that is linked to the pedal assembly. The hub includes a coaster brake, and a coaster brake drive adapted always to propel the cycle forwardly when the drive is turned forwardly, and to apply the brake when it is turned rearwardly. A unidirectional clutch is interposed between the hub sprocket and the coaster brake drive. In the freewheeling operation, the clutch is permitted to operate in its standard mode, namely to propel the cycle when the pedal assembly is driven forwardly and to freewheel rearwardly, both relative to the coaster brake drive.
To convert the hub to the coaster brake mode, the clutch is disabled in the sense that it can no longer permit freewheeling in one direction effectively joining the hub sprocket arm coaster brake drive so that the hub sprocket directly drives the coaster brake drive in both directions. In the preferred embodiment, this is accomplished by interconnecting two relatively rotatable parts of the clutch.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which: